1. Field of the Invention
The present invention relates to a hydrodynamic compression or cutting tool.
2. Description of the Related Art
Hydrodynamic compression and/or cutting tools are often used to perform determined connection operations, e.g. compressing connectors on electrical wires or for hydraulic pipes, compressing rivets, or for cutting operations, e.g. cutting electrical wires during electrical system installation and maintenance.
Such tools usually comprise an electrical motor supplied by an accumulator and a hydraulic pipe which causes an increase of pressure of a hydraulic liquid acting on an actuating piston to move it against the bias of a pressure spring. In turn, the actuating piston is connected to a movable jaw so as to move it during the compression operation towards a fixed jaw of the tool. The jaws may be shaped and/or provided with interchangeable accessory elements so as to adapt to a particular object, e.g. an electrical contact to be compressed or a metallic bar to be cut.
The operating modes of the compression and cutting tools are determined by a condition of interruption of the pressurization of the hydraulic liquid to a the already closed jaws or at completion of the compression or of the cutting, and by a return mode of the hydraulic fluid towards a tank of the hydraulic pump, which allows the actuating piston to return towards a rest position thereof and thus the opening of the jaws.
Hydrodynamic compression tools with a so-called manual return are known, in which, after the end of the pressurization of the hydraulic liquid and the consequent completion of the working cycle, the return of the hydraulic liquid and the consequent return of the jaws towards their open position occurs by pressing a manual release button for all the time needed to reach the required opening width of the jaws. The manual release button acts by means of a manual release mechanism on the return valve so as to keep it open when the manual release button is pressed and to close it when the release button is not pressed.
The manual return ensures complete control of the jaw return to the operator but indeed requires the release button to be pressed for the entire jaw opening time.
Hydrodynamic compression tools with a so-called automatic return are also known, in which, after the end of the pressurization of the hydraulic liquid and the consequent completion of the working cycle, the return of the hydraulic liquid and the consequent return of the jaws towards their open position occurs by means of a maximum pressure valve which opens initially with the reaching of a maximum pressure of the hydraulic liquid and which is kept open by means of a stop mechanism of the shutter of the maximum pressure valve in the open condition or by means of the floating of the valve.
The known automatic return occurs without voluntary activation by the operator and deprives the operator from the possibility of verifying the final state reached after the completion of the compression or cutting or partial cutting cycle.